This invention relates generally to the field of electrically conductive wires and cables, and more particularly to an improved low noise cable suitable for use in communications and signal transmission.
So called low noise cables of known type are characterized in the provision of a semi-conducting layer applied over the dielectric or insulative material which encloses the metal conductor or conductors. With such construction, there has been a significant reduction in piezo induced, that is to say mechanically generated, noise. The use of such cables, however, is not ideal, as there has been considerable need for improvement, particularly when the cables are used in conjunction with solid state equipment which requires very low voltage and amperage levels during operation. Further, a basic problem, that of pyro generated noise has not been resolved in such cables, as compared with conventional cables.
The Burney U.S. Pat. No. 3,670,058 of June 13, 1972, describes an early attempt at solving the problem, in the provision of a method of reducing or minimizing noise in co-axial cable including the steps of heating the cable sufficiently to soften the dielectric filler, applying an alternating voltage across the inner and outer conductors of the cable, and cooling the cable while maintaining the voltage across it. This has resulted in substantial reduction of noise, but not a total elimination of residual current.